It could extend out after the helo is airborne to pretty much any size you want.1) physical limitation of antennas' size
meh crosswind not necessarily helps, size antenna cannot be
It will spot low flying targets out to extended ranges...2) platform service ceiling
extended comparing to ship true. But unless you have OTH radar - radar horizon is for everybody. And this depends on ceiling...
Could land on the back of any ship in the carrier group to refuel if needed...3) flight duration
(1) the one of approaches is using of conformal antennas.
(2) +(3) Since in the air will be only AEW component thus IMHO the best option here using long duration drones. They dont need crew to rest, train... can fly for a long time. Will it be helo or tilltrotor dunno. I am sure tho that it will be a UAV vstol platform. Simly 2-3 tons of payload + tltrotor give flexibility and saves costs.
If it is going to be a UAV then HALE makes more sense.... with inflight refueling from carrier based fighters...
As long as you can lauch HALE form your ships it would be a good idea. Or airship ;-)